FocusHandler
class FocusHandler(isMessageFn: (Int) -> Boolean = { typeNumber ->
typeNumber == StoryTypes.TEXT.type.number ||
typeNumber == StoryTypes.TEXT_BOX.type.number ||
typeNumber == StoryTypes.CHECK_ITEM.type.number
})
This class is responsible to control the focus of the edition of story. (example: If the text of a story is being edited, this story has the current focus.)